EXPRESSION AND CHARACTERIZATION OF THE MULTIPLIED, RECOMBINANT PRES1 ANTIGEN OF HEPATITIS-B VIRUS

The amino acid sequence encoded by the preS1 region of hepatitis B vir us genome is expressed on the surface of virions and subviral particle s. The preS1 region is involved in the recognition of specific recepto rs responsible for the attachment of HBV to the host cell. The cell re ceptor binding site was assigned to the preS1 (20-47 aa) fragment. In order to obtain a large quantity of preS1 binding domains of HBV the e xpression vector pWX4 was constructed. It contains four tandemly joine d DNA sequences, each coding for preS1 (20-49 aa), fused with the 3' e nd of a DNA fragment coding for 450 aa of beta-galactosidase. E. coli cells transformed with this vector produce fusion protein beta-gal-pre Slx4 in the form of inclusion bodies. Owing to the specific trypsin di gestion, the preSlx4 domain was cleaved from the fusion protein. The r esulting product, a 16 kDa protein, was isolated and purified by anion exchange chromatography. The presence of four Asp-ro bonds in this se quence and the primary structure of the first 28 N-terminal amino acid s were determined. Following the confirmation of the antigenic propert ies, the recombinant preS1 protein was used for detection of the anti- preS1 response in sera from HBV infected patients.